import time
import torch
import numpy as np
import matplotlib

matplotlib.use('agg')
import matplotlib.pyplot as plt
import random


class AverageMeter(object):
    """Computes and stores the average and current value"""
    def __init__(self):
        self.reset()

    def reset(self):
        self.val = 0
        self.avg = 0
        self.sum = 0
        self.count = 0

    def update(self, val, n=1):
        self.val = val
        self.sum += val * n
        self.count += n
        self.avg = self.sum / self.count


class RecorderMeter(object):
    """Computes and stores the minimum loss value and its epoch index"""
    def __init__(self, total_epoch):
        self.reset(total_epoch)

    def reset(self, total_epoch):
        assert total_epoch > 0
        self.total_epoch = total_epoch
        self.current_epoch = 0
        self.epoch_losses = np.zeros((self.total_epoch, 2), dtype=np.float32)  # [epoch, train/val]
        self.epoch_losses = self.epoch_losses - 1

        self.epoch_accuracy = np.zeros((self.total_epoch, 2),
                                       dtype=np.float32)  # [epoch, train/val]
        self.epoch_accuracy = self.epoch_accuracy

    def update(self, idx, train_loss, train_acc, val_loss, val_acc):
        assert idx >= 0 and idx < self.total_epoch, 'total_epoch : {} , but update with the {} index'.format(
            self.total_epoch, idx)
        self.epoch_losses[idx, 0] = train_loss
        self.epoch_losses[idx, 1] = val_loss
        self.epoch_accuracy[idx, 0] = train_acc
        self.epoch_accuracy[idx, 1] = val_acc
        self.current_epoch = idx + 1
        return self.max_accuracy(False) == val_acc

    def max_accuracy(self, istrain):
        if self.current_epoch <= 0: return 0
        if istrain: return self.epoch_accuracy[:self.current_epoch, 0].max()
        else: return self.epoch_accuracy[:self.current_epoch, 1].max()

    def plot_curve(self, save_path):
        title = 'the accuracy/loss curve of train/val'
        dpi = 80
        width, height = 1200, 800
        legend_fontsize = 10
        scale_distance = 48.8
        figsize = width / float(dpi), height / float(dpi)

        fig = plt.figure(figsize=figsize)
        x_axis = np.array([i for i in range(self.total_epoch)])  # epochs
        y_axis = np.zeros(self.total_epoch)

        plt.xlim(0, self.total_epoch)
        plt.ylim(0, 100)
        interval_y = 5
        interval_x = 5
        plt.xticks(np.arange(0, self.total_epoch + interval_x, interval_x))
        plt.yticks(np.arange(0, 100 + interval_y, interval_y))
        plt.grid()
        plt.title(title, fontsize=20)
        plt.xlabel('the training epoch', fontsize=16)
        plt.ylabel('accuracy', fontsize=16)

        y_axis[:] = self.epoch_accuracy[:, 0]
        plt.plot(x_axis, y_axis, color='g', linestyle='-', label='train-accuracy', lw=2)
        plt.legend(loc=4, fontsize=legend_fontsize)

        y_axis[:] = self.epoch_accuracy[:, 1]
        plt.plot(x_axis, y_axis, color='y', linestyle='-', label='valid-accuracy', lw=2)
        plt.legend(loc=4, fontsize=legend_fontsize)

        y_axis[:] = self.epoch_losses[:, 0]
        plt.plot(x_axis, y_axis * 50, color='g', linestyle=':', label='train-loss-x50', lw=2)
        plt.legend(loc=4, fontsize=legend_fontsize)

        y_axis[:] = self.epoch_losses[:, 1]
        plt.plot(x_axis, y_axis * 50, color='y', linestyle=':', label='valid-loss-x50', lw=2)
        plt.legend(loc=4, fontsize=legend_fontsize)

        if save_path is not None:
            fig.savefig(save_path, dpi=dpi, bbox_inches='tight')
            print('---- save figure {} into {}'.format(title, save_path))
        plt.close(fig)


def time_string():
    ISOTIMEFORMAT = '%Y-%m-%d %X'
    string = '[{}]'.format(time.strftime(ISOTIMEFORMAT, time.gmtime(time.time())))
    return string


def convert_secs2time(epoch_time):
    need_hour = int(epoch_time / 3600)
    need_mins = int((epoch_time - 3600 * need_hour) / 60)
    need_secs = int(epoch_time - 3600 * need_hour - 60 * need_mins)
    return need_hour, need_mins, need_secs


def time_file_str():
    ISOTIMEFORMAT = '%Y-%m-%d'
    string = '{}'.format(time.strftime(ISOTIMEFORMAT, time.gmtime(time.time())))
    return string + '-{}'.format(random.randint(1, 10000))


def to_one_hot(inp, num_classes, device='cuda'):
    y_onehot = torch.zeros((inp.size(0), num_classes), dtype=torch.float32, device=device)
    y_onehot.scatter_(1, inp.unsqueeze(1), 1)

    return y_onehot


def distance(z, dist_type='l2'):
    '''Return distance matrix between vectors'''
    with torch.no_grad():
        diff = z.unsqueeze(1) - z.unsqueeze(0)
        if dist_type[:2] == 'l2':
            A_dist = (diff**2).sum(-1)
            if dist_type == 'l2':
                A_dist = torch.sqrt(A_dist)
            elif dist_type == 'l22':
                pass
        elif dist_type == 'l1':
            A_dist = diff.abs().sum(-1)
        elif dist_type == 'linf':
            A_dist = diff.abs().max(-1)[0]
        else:
            return None
    return A_dist
